1. Field of the Invention
The present invention relates to a rotary head apparatus and, more particularly, to a rotary head apparatus having a function to verify recorded data.
2. Description of Related Art
FIG. 5 is a sectional view of a prior art rotary head apparatus. FIG. 6 is an explanatory view of the prior art rotary head apparatus. And FIG. 7 is a timing chart showing a recording signal and a reproducing signal of the prior art rotary head apparatus which are plotted on angle axes.
The magnetic recording-reproducing device mounted with this type of rotary head apparatus is used in backing up data in a computer, and has a verifying function to perform a read-after-write operation. The prior art rotary head apparatus, as shown in FIG. 5, has a stationary drum K mounted in a lower position, a rotary drum D mounted above the stationary drum K, and a motor M mounted above the rotary drum D. The stationary drum K has a cylindrical stationary shaft 51 fixed at center thereof. The rotary drum D is rotatable on the center of the stationary shaft 51 and fitted with four magnetic heads 52.
These four magnetic heads 52 are each comprised of a recording magnetic head W including a couple of magnetic head elements and a reproducing magnetic head R including a couple of magnetic head elements. For the recording magnetic head W a magnetic head called a combination head disposed adjacently to the couple of magnetic head elements Wa and Wb is used. Similarly, for the reproducing magnetic head R there is used a combination head comprising a couple of magnetic head elements Ra and Rb. The two magnetic heads W and R are symmetrically arranged on both sides of the stationary shaft 51 at center.
A rotary transformer 53 supplies a recording signal at the time of recording to the four magnetic heads 52 and takes out a reproducing signal at the time of reproduction. The rotary transformer 53 is comprised of a transformer 53a on the stationary side and a transformer 53b on the rotary side. These rotary transformers 53 are disposed between the stationary drum K and the rotary drum D. The transformer on the stationary side 53a is mounted on the stationary drum K. The transformer on the rotary side 53b is mounted on the rotary drum D and turns together with the rotating drum D.
Two ball bearings 55, 55 are mounted on both sides of a center hole 56 of the rotary drum D, so that the rotary drum D will be rotatable.
The motor M is comprised of a stator section S supported on the stationary shaft 51 and a rotor section L mounted on the rotary drum D. The rotor section L is mounted on the top of the rotary drum D and the stator section S is secured on the stationary shaft 51 so as to be above the rotary section L.
The stator section S is comprised of a cylindrical stationary member 57 inserted on the stationary shaft 51, a motor control circuit board 58 mounted with a motor control circuit, and a core 60 of a magnetic metal fitted with a coil 59.
The rotor section L is formed in a shape of cup and has a rotor motor yoke 61 attached on the rotary drum D and a cylindrical magnet 62 fixedly bonded to the inside of the side wall of the rotor motor yoke 61. The core 60 is disposed inside the cylindrical magnet 62; the core 60 and the magnet 62 are oppositely arranged with the same amount of clearance provided all around.
The above-described prior art rotary head apparatus is of such a design that the rotary drum D is turned by power from the motor M; with the rotation of the rotary drum D the four magnetic heads 52 also are turned to move a magnetic tape T pressed with a predetermined pressure in contact with these magnetic heads 52, thereby performing recording or reproduction.
As shown in FIG. 6, the prior art rotary head apparatus is driven to perform read-after-write operation. At this time the rotary drum apparatus turns through an effective wrap angle P of about 180 degrees, that is, through the angle for signal recording into, or reproducing from, the magnetic tape T. Furthermore, information, when recorded on the magnetic tape T by the recording magnetic head W, is recorded by the magnetic head W during a turn from 0xc2x0 (the reference position in which the recording magnetic head W of the rotary drum D faces the magnetic tape T as shown in the timing chart in FIG. 7) to 180 xc2x0 of the rotary drum D; that is, magnetic head elements Wa and Wb operate to record nearly simultaneously the recording magnetic head W of the rotary drum D. The magnetic head elements Wa and Wb are arranged a little apart from each other, and therefore there is an about 1xc2x0 to 2xc2x0 delay on the angle axis. Consequently the magnetic head element Wb follows the magnetic head element Wa in the direction of rotation (i.e., direction of recording).
Reproduction using the reproducing magnetic head R is a read-after-write operation to check to see whether or not signal recording on the magnetic tape T is done properly in accordance with a reproducing signal. The reproducing magnetic head R and the recording magnetic head W are arranged at a spacing of 180xc2x0 on the outer peripheral surface of the rotary drum D; the reproducing angle, therefore, will not overlap the recording angle at which the recording signal is recorded. That is, while the rotary drum D is turning from 180xc2x0 to 360xc2x0 (i.e., 0xc2x0) within which angle no recording is done by the recording magnetic head W, the reproducing magnetic head R reproduces the signal recorded by the recording magnetic head W. The recording signal to be reproduced by the magnetic head element Ra at this time is a signal recorded by the magnetic head element Wa, and the signal to be reproduced by the magnetic head element Rb is a signal recorded by the magnetic head element Wb. In this manner the read-after-write operation is repeated.
In this type of rotary head apparatus, however, recording is done by the recording magnetic head W only within the range of 180xc2x0 during a 360xc2x0 turn (one turn) of the rotary drum D as shown in FIG. 7. Furthermore, reproduction for the read-after-write operation that can be done by the reproducing magnetic head R is similarly 180xc2x0. In a rotary head apparatus having the magnetic head 52 including a couple of combination heads, the effective wrap angle P is about 180xc2x0, and therefore the speed of rotation, that is, the time for data recording and reproducing for read-after-write operation can not be decreased as far as the same constitution as mentioned above is employed. Consequently the rate of data transfer also can not be improved.
Various kinds of means have been proposed in an attempt to improve the rate of data transfer; of these means there has been known a means for improving the rate of data transfer by a rotary head apparatus using eight magnetic head elements including two combination heads of the first and second recording magnetic heads W1 and W2 and two combination heads of the first and second reproducing magnetic heads R1 and R2. The recording magnetic head W1 is comprised of a combination head with a couple of magnetic head elements W1a and W1b adjacently arranged. Similarly the recording magnetic head W2 is comprised of a couple of magnetic head elements W2a and W2b; the reproducing magnetic head R1 is comprised of a couple of magnetic head elements R1a and R1b; and the reproducing magnetic head R2 is comprised of a couple of magnetic head elements R2a and R2b. 
The couple of recording magnetic heads W1 and W2 are arranged symmetrically with the stationary shaft 51 placed at center. In a similar manner the couple of reproducing magnetic heads R1 and R2 are also symmetrically positioned with the stationary shaft 51 at center. The four magnetic heads 52 are arranged at an equal spacing of 90xc2x0 on the outer peripheral surface of the cylindrical rotary drum D in the order of W1, R1, W2 and R2 when viewed clockwise.
According to the rotary head apparatus thus constituted, the recording magnetic head and the reproducing magnetic head come into contact with, and slide on, the magnetic tape T at the same timing, so that recording and reproducing, i.e., the read-after-write operation, can be performed simultaneously, thereby enabling to improve the data transfer rate. For instance, when the effective wrap angle P of the magnetic tape T is around 180xc2x0, the magnetic tape T thus wrapped runs in contact with the recording head including one combination head and also with the reproducing head including one combination head at any timing. That is, recording a recording signal is done by means of the recording magnetic head and at the same time reproducing operation is performed by means of the reproducing magnetic head. At any angle of rotation, therefore, recording and reproducing the read-after-write operation are continuously carried out, thereby increasing the rate of data transfer twice higher as compared with the prior art rotary head apparatus.
One combination head is provided with two magnetic head elements. Therefore, when four combination heads are used, the rotary transformer needs eight signal channels so that the magnetic head element s can send and receive different signals. Also provided is a preamplifier circuit which amplifies a reproducing signal output to reduce a noise effect caused by interference from the recording magnetic head. Furthermore, one power supply channel for supplying the power to the preamplifier circuit is required. That is, nine channels in all are required. In the magnetic recording-reproducing device including a downsized rotary head apparatus, the rotary transformer has also been downsized. In such a rotary head apparatus, therefore, it is difficult to provide nine channels. If it is possible to provide nine channels, adjacent channels are arranged very close to each other; therefore because the recording signal and the reproducing signal are high-frequency signals, the signals in the adjacent channels will not be affected, resulting in an increased signal noise. Furthermore, the rotary transformer, if provided with nine channels, will become larger in size and accordingly high in cost, thus upsizing the rotary head apparatus. That is, it will become hard to downsize the rotary head apparatus. Consequently it is hard to improve the rate of data transfer while increasing the number of the combination heads.
It is an object of the present invention to provide a rotary head apparatus which has a verifying function and a high data transfer rate. It is another object of the present invention to provide a rotary head apparatus which can be downsized. It is further another object of the present invention to provide a rotary head apparatus capable of reducing a noise effect.
As the first means for solving the above-described problem, the rotary head apparatus of the present invention is provided with a first set of recording magnetic head including two magnetic head elements, a second set of recording magnetic head including two magnetic head elements, a first set of reproducing magnetic head including two magnetic head elements, a second set of reproducing magnetic head including two magnetic head elements, and a rotary transformer mounted on the drum for transmitting a signal to the magnetic heads. The first set of reproducing magnetic head and the second set of reproducing magnetic head are oppositely arranged on both sides of the rotating shaft. Also the first set of recording magnetic head and the second set of recording magnetic head are oppositely arranged on both sides of the rotating shaft. One of the couple of magnetic head elements of the first set or recording magnetic head and one of the couple of magnetic head elements of the second set of recording magnetic head are connected to the first channel of the rotary transformer; and the other one of the couple of magnetic head elements of the first set of recording magnetic head and the other one of the couple of magnetic head elements of the second set of recording magnet head are connected to the second channel of the rotary transformer, so that recording and reproducing can be done at the same time.
Furthermore, in the rotary head apparatus of the present invention, as the second means of solution, one of the couple of magnetic head elements of the first set of reproducing magnetic head and one of the couple of magnetic head elements of the second set of reproducing magnetic head are connected to the third channel of the rotary transformer. Also the other couple of magnetic head elements of the first set of reproducing magnetic head and the other couple of magnetic head elements of the second set of reproducing magnetic head are connected to the fourth channel of the rotary.
Furthermore, the rotary head apparatus of the present invention, as the third means of solution, is provided with a preamplifier circuit connected to the magnetic head element of the reproducing magnetic head and an output changeover circuit; and the fifth channel of the rotary transformer is provided with a channel for selectively supplying the power to the preamplifier circuit.